This article is the subject of a legal complaint made on behalf of Sheikh Sadeg Elgariani.

Libya’s highest spiritual leader, the grand mufti Sheikh Sadik Al-Ghariani, has been banned from entering the UK after it emerged he had been helping direct the Islamist-led takeover of Tripoli from England.

Speaking from the UK via the Libyan television station Tanasuh, the radical cleric celebrated the violent capture of Tripoli by Islamist militia force Libya Dawn, and ordered a widening of the rebellion.

Home Office officials examined his broadcasts and issued a Risk and Liaison Overseas Network (Ralon) order excluding him from entering the UK.

A Home Office spokesman said: “We do not routinely comment on individual cases. But we are clear that those who seek to foster hatred or promote terrorism are not welcome in the United Kingdom. We will take action against those who represent a threat to our society or seek to subvert our shared values.”

It is not known where in the UK Ghariani was living for several months earlier this year, but he also communicates with his supporters via the website, Tanasuh.com, registered to his son at a whitewashed terraced house near Exeter city centre.

Speaking via Tanasuh TV, the influential cleric broadcast to jihadi militants battling government forces in Tripoli. “I congratulate the revolutionaries in their victory, I give blessing to the martyrs,” he told his followers the day after Tripoli fell to Libya Dawn.

Libya has endured its worst violence since the 2011 overthrow of Muammar Gaddafi, after Libya Dawn, an alliance of Islamist and Misrata forces, swept into the capital, set fire to buildings and arrested opponents, as the administration of Prime Minister Abdullah al-Thinni fled to eastern parts of the country.

Libya Dawn does not accept the elected parliament, the House of Representatives, which is recognised as Libya’s legitimate government by the United Nations and the international community. Instead, Libya Dawn supports the former parliament, the General National Council, based in Tripoli.

Whitehall sources confirmed in August that Ghariani was in the UK on a private visit. He is thought to have been in the UK for some months where he may have undergone private medical treatment. Reports in Libya suggest the grand mufti has recently been treated for cataracts.

International envoys regard Ghariani as an influential voice in Islamist circles, and earlier this week he met in Tripoli with UN Libya envoy Bernadino Leon to discuss peace proposals. War continues to rage south of the capital and in the eastern city of Benghazi, where air strikes on Thursday pounded Islamist militia positions.

Peace talks are stalled over the refusal of Libya Dawn to recognise the parliament, elected in June.

Earlier this month, Libya’s government called on the parliament in Tobruk, to fire Ghariani from his position, angry about a recent statement in which he accused the authorities of seeking support abroad for foreign military intervention.

Ghariani has won both support and criticism in Libya for his calls for male and female students to be separated at universities, for bans on Libyan women marrying foreigners and for seeking to regulate the import of lingerie.

• Lawyers for Sheikh Al-Ghariani contacted us after publication, in July 2015, taking issue with this article. They stated that he stands against terrorism, violence and religious extremism and has called for unity in Libya. They say that events described as ‘the capture of Tripoli by an Islamist militia force’ in fact constitute the rescue of Tripoli, under the authority of the General National Congress, from unlawful forces loyal to General Haftar. They also pointed out that Sheikh Al-Ghariani’s speech of 24 August 2014 was broadcast via a Libyan TV station called Tanasuh TV, not via a website called Tanasuh.com. The article has been amended to correct this, as well as to include further political background.